(Bloomberg) — The Winklevoss twins have taken on their next project in the cryptocurrency world: regulation. The brothers, who run the Gemini exchange for trading Bitcoin and Ether, have submitted a proposal to create the Virtual Commodity Association, a self-regulatory organization meant to police digital-currency markets and custodians. The non-profit group would aim to develop industry standards, promote transparency and work with regulators including the U.S. Commodity Futures Trading Commission to prevent fraud. “The promise of virtual commodities and their impact on the future will be profound — but individuals and institutions need to feel safe and secure when transacting,”…